before there was anything like "aliens" people described being visited by angels and demons.by the time the first alien stories/movies/books appeared people started being "abducted" the shape of the alien that we see in all these pictures didn't exist yet, they were more robotic and some were big hairy things, the UFO itself was changing in the same fashion, from long objects to the disc they see today.it is still changing as more people claim to see a triangular shaped UFO.so this explains why the reports are all somewhat the same.and also explains why its pretty much bullshit.